ITV Wales understands the source of a fly infestation in Llanelli which has plagued residents is a scrap metal recycling plant operated by AMG Resources.
Carmarthenshire Council worked alongside independent pest experts to identify the plant which is located near the area affected.
Residents complaining of the infestation described the infestation as 'absolute hell'
The council are now spray-treating the area under the supervision of environmental health officers. They said it could take a few days for the treatment to take effect but will continue to offer support to vulnerable people, including the elderly and disabled, affected by the issue.
AMG Resources has been contacted for a comment.